1. Field of Invention
The present invention relates to a lighting device and an electronic device using the lighting device. More specifically, the present invention relates to a lighting device having an organic electroluminescent (hereinafter referred to as an xe2x80x9corganic ELxe2x80x9d) device and capable of simultaneously illuminating a transmission-type display unit, such as a liquid crystal display unit, input buttons, etc., on a mobile telephone and the like, and to an electronic device using the lighting device.
2. Description of Related Art
A related lighting device capable of illuminating a transmission-type display unit, such as a liquid crystal display unit, and input buttons is described with reference to FIG. 6. As shown in this figure, the conventional lighting device is divided into a part for illuminating a liquid crystal display unit 203 with a light source 202a adjacent to an end face of a light-guide panel 201, and a part for illuminating input buttons 206 using light sources 202b mounted on a switch substrate 207. About two to eight light-emitting diodes (LEDs) are used for the light source 202a, and six to fifteen light emitting diodes (LEDs) are used for the light sources 202b. 
In the above-described lighting device, a light source for illuminating the liquid crystal display unit part is separate from a light source for illuminating the other parts, and these sources employ a number of light-emitting diodes (LEDs), respectively. However, these have problems of complicated structure as well as low uniformity in brightness.
The present invention is intended to at least solve the foregoing problems. It is an object thereof to provide a lighting device, which is less expensive and has high uniformity in brightness, in which an organic EL lighting device is used to illuminate a liquid crystal display unit while a light beam emitted from its end face is used to illuminate the other components, and to provide an electronic device using the same.
A lighting device according to one exemplary embodiment of the present invention includes an organic electroluminescent element, and a transparent substrate, the substrate having a first principal plane on which light from the organic electroluminescent element is incident, and a second principal plane. The light incident on the substrate includes first light emitted from a second principal plane of the substrate, and second light emitted from a plane other than the first and second principal planes. The first and second lights may be used to illuminate different objects to be illuminated. With this arrangement, backlighting with high uniformity, for liquid crystal displays, etc., and illumination for the other parts can be realized with a simple structure.
In a lighting device according to another exemplary embodiment of the present invention, the lighting device described above further includes a reflector member for reflecting a portion of the first light. A third light reflected by the reflector member may be used to illuminate the same object to be illuminated by the second light. Therefore, in addition to light emitted from an end of a substrate, light transmitted by the substrate can also be introduced by a reflector portion of a light-guide element to an object to be objected, thus achieving efficient illumination.
In a lighting device according to another exemplary embodiment of the present invention, the lighting device described above further includes a reflector member for transmitting a first light component of the first light having a specific wavelength, and for reflecting a second light component other than the first light component. The first light component and the second light component may be used to illuminate different objects to be illuminated. Therefore, for example, a liquid crystal display unit can be illuminated by green light while an object to be illuminated can be illuminated by red light at the same time.
In a lighting device according to another exemplary embodiment of the present invention, the organic electroluminescent element includes a pixel region on which the first light is generated to display arbitrary information, and an illuminator region on which the second light is generated to illuminate an object to be illuminated. Therefore, displaying arbitrary information and illuminating an object to be illuminated can be realized by a single lighting device at the same time.
An electronic device according to one exemplary embodiment of the present invention may include the lighting device described above a display unit illuminated by the first light to display arbitrary information, and a key input unit illuminated by the second light. A transmission-type display unit such as a liquid crystal display unit, and input key buttons on an electronic device such as a mobile telephone can be illuminated at the same time.